Sustainable Air Quality: Studies Based on Fluid Mechanics and Compressor-Less Water-Based Cooling

Dear Colleagues,

Driven by economic development and the growing demand for thermal comfort, the energy consumption of Ventilation and Air Conditioning (HVAC) systems is rapidly increasing. The utilization of HVAC has improved people's quality of living, but it has also produced some negative effects on the natural environment. Most HVAC systems, driven by conventional vapor-compression refrigeration systems, use refrigerants based on chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) with high Global Warming Potential (GWP). Additionally, conventional vapor-compression refrigeration systems are energy-intensive and consume around 50% of the total supplied energy, which indirectly leads to high carbon emissions from generating power by burning fossil fuels. Owing to the high dependency on fossil fuel burning in current energy systems, this technology is regarded as neither sustainable nor environmentally friendly. The serious effects of climate change caused by the greenhouse effect are of great concern to the international community.

Compressor-less Water-based Cooling, which makes full use of dry air energy in the ambient air and removes heat through the water evaporation process, has been regarded as a promising solution to substitute conventional air conditioning. Compared with conventional air conditioning systems, the advantages of this cooling technology are worth being emphasized because it does not employ any compressors or environmentally harmful refrigerants. Theoretically, the technology can achieve great energy savings based on reasonable optimization design. Additionally, the working media of the heat and mass transfer processes are water and air, so it is an environmentally friendly cooling method. This technology is highly relevant to plenty of fields. As a passive cooling device, it can be used for cooling production, energy recovery, and ventilation in buildings. With proper modification and combination, water desalination can also be achieved. In addition, the technology's use for some agricultural storage issues has also been demonstrated.

Therefore, this Special Issue is organized to add recent advances to the information on the studies based on fluid mechanics and compressor-less water-based cooling. We invite the authors to raise awareness of different aspects of the problem or to contribute relevant knowledge on (but not limited to) any of the aspects mentioned below:

• Advanced compressor-less water-based cooling system technologies and applications;
• Novel materials and structures for water-based evaporative cooling devices;
• Sustainable multi-stage hybrid cooling systems;
• Surface wettability theory;
• Indoor air quality;
• System optimal control method;
• Fluid flow, heat transfer, and mass transfer analysis;
• Energy, economy, and environment analysis;
• Manufacturing and commercialization.

Dr. Yangda Wan
Dr. Jie Lin
Dr. Weidong Chen
Guest Editors

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